A goblin, o, is likely to be among the very first monsters you meet, and often carries an orcish helm and an orcish dagger (50% chance of each[1]). They are not a significant threat, unless they are armed with a deadly wand, though that is an unlikely occurrence.

For in-game purposes goblins are orcs including being subject to the effects of Sting and Orcrist. Their corpses are useful for orc characters since they can be sacrificed to convert altars to the chaotic alignment.

Now goblins are cruel, wicked, and bad-hearted. They make
no beautiful things, but they make many clever ones. They
can tunnel and mine as well as any but the most skilled
dwarves, when they take the trouble, though they are usually
untidy and dirty. Hammers, axes, swords, daggers, pickaxes,
tongs, and also instruments of torture, they make very well,
or get other people to make to their design, prisoners and
slaves that have to work till they die for want of air and
light.